Thousands of air passengers in Asia were stranded for a second day Saturday because of ash from an Icelandic volcano that paralyzed European airports.

Australia’s Qantas cancelled all flights to Europe on Saturday, and passengers were being offered refunds or seats on the next available flight. The airline said it was not known when flights would resume, and warned of further delays as European airports struggle to clear a heavy backlog of flights.

The massive cloud of ash started spreading over northern Europe on Thursday, and officials don’t known when the skies in one of aviation’s most congested areas will be safe again. Volcanic ash limits visibility and is capable of knocking out jet engines.

Airlines cancelled about 60 flights between Asia and Europe on Friday, and more were expected Saturday as a vast, invisible plume of grit drifted over Europe.

Southern Iceland’s Eyjafjallajokull (ay—yah—FYAH’—plah—yer—kuh—duhl) volcano eruption sent ash several miles (kilometers) into the air, with winds pushing the plume south and east across Britain, Ireland, Scandinavia and into the heart of Europe. Two—thirds of flights in Europe were cancelled, sending hundreds of thousands of stranded passengers in search of hotel rooms, train tickets or rental cars Friday.

In Asia, Japanese carriers had to cancel 15 flights with nearly 4,000 passengers Friday. In Seoul, 12 flights were canceled, and two flights en route to Europe were forced to turn around. Singapore Airlines canceled seven flights to Europe.

Qantas said it was providing accommodation and food vouchers to some 1,750 passengers stuck since Friday -- about 1,000 in Singapore and 350 each in Hong Kong and Bangkok. Qantas said its flights to Asian hubs would continue with the exception of one service to Singapore.

Fifteen flights between Hong Kong and Europe were canceled on Friday. Air China canceled or delayed several round—trip flights from Beijing and Shanghai to European destinations.

Air New Zealand warned travelers flying to Europe to defer their plans, as it canceled two flights through London and diverted a third to Germany.